1. Field of the Invention
The present invention relates to a Valley Alignment (VA) mode Liquid Crystal Display (LCD), and more particularly, to a Valley Vertical Alignment (VVA) mode LCD having jagged valleys.
2. Description of the Prior Art
As is well known in the art, a VA mode LCD has been proposed to improve a narrow angular field and a low response speed of a Twisted Nematic (TN) mode LCD. Though not shown, the VA mode LCD has upper and lower substrates, each of which is equipped with a liquid crystal drive electrode, a liquid crystal layer interposed between the upper and lower substrates and having liquid crystal molecules with a negative dielectric anisotropy, vertical orientation layers arranged, respectively, in opposite faces of the upper and lower substrates, and polarizers attached, respectively, to outer faces of the upper and lower substrates. The polarizers have polarization axes which intersect with each other.
The VA mode LCD also has liquid crystal molecules arrayed perpendicularly to the substrate under the influence of the vertical orientation layers to realize a dark screen in relation to the upper and lower polarizers having the perpendicularly intersected polarization axes until an electric field is generated. As an electric field is created between liquid crystal drive electrodes in the upper and lower substrates, the liquid crystal molecules are distorted in which long axes thereof are oriented perpendicular to the direction of the electric field so that light leaks through the distorted liquid crystal molecules to realize a white screen.
However, the VA mode LCD has a drawback that the liquid crystal molecules have a dielectric anisotropy and thus the screen forms different images according to angular fields. For example, before creation of the electric field, the liquid crystal molecules are oriented perpendicular to the substrates to obtain a completely dark screen when seen from the front of the screen. However, light leaks through lateral portions of the screen degrading image quality.
Therefore, in order to compensate quality degradation resulting from the dielectric anisotropy of the liquid crystal molecules, there have been proposed various types of VA mode LCDs, for instance, a Multidomain Vertical Alignment (MVA) mode LCD of Fujitsu.
However, though not shown and described in detail, the MVA mode LCD is provided with liquid crystal drive electrodes in the form of protrusions or slits capable of distorting an electric field, respectively, in upper and lower substrates. As a result, there is a drawback in that one more mask is needed to complicate a fabrication process and increase fabrication cost.
Accordingly, in order to solve these problems, a Valley Vertical Alignment (VVA) mode LCD was filed by the assignee of the invention as Korean Patent Application Serial No. 2002-36490, Jun. 27, 2002, by which a V-shaped valley is formed in a color resin layer to create multiple domains.
FIG. 1 illustrates an arrangement of liquid crystal molecules in a conventional VVA mode LCD, in which the reference numeral 1 indicates a slit or protrusion in a lower substrate, 2 indicates a V-shaped groove or valley in the lower substrate, and 3 indicates liquid crystal molecules.
In the VVA mode LCD, a V-shaped valley is formed in a color resin layer, which is also provided with a counter electrode and a vertical orientation layer formed on the color resin layer.
The VVA mode LCD has an electrode structure, which can cause distortion to an electromagnetic field to form multiple domains thereby reducing optical leak according to angular fields. However, because the V-shaped valley is formed via mask change in formation of the color resin layer, the VVA mode LCD does not require any additional mask and thus does not complicate a fabrication process or increase cost as a result of the additional mask.
In the VVA mode LCD, it is required to orient the liquid crystal molecules to lie perpendicularly to the V-shaped valley in application of current in order to form the multiple domains for improving angular field characteristics. However, in the conventional VVA mode LCD, the symmetric peripheral structure of the V-shaped valley fails to stably orient the liquid crystal molecules perpendicular to the V-shaped valley in application of current. As a result, this obstructs formation of stable multiple domains, thereby causing a problem of image quality degradation thanks to creation of a dislination line 10 as shown in FIG. 1.